For many years, practitioners in the medical treatment and medical device arts have endeavored to provide artificial heart devices constructed to replace a failed or failing heart within a recipient. The most basic need is the creation of a replacement pumping device which is capable of performing the basic blood pumping and circulation functions of the natural heart.
Early attempts to provide a sustainable heart replacement were severely limited by the available technologies and the state of the art at that time. Devices proved to be generally too large and unwieldy and, for the most part, impractical. With the continuing advances in the related technologies and creative arts, heart replacement devices became smaller, more reliable and, in some instances, at least partially implantable within the recipient. Such “implantable” devices have generally remained hybrid devices in that the actual pump may be implanted within the recipient while additional support apparatus remains external to the patient and remains connected to the implanted device by a plurality of connecting wires and hoses.
Because of the complexity of human body systems and the complications and consequences of heart replacement device failure, the requirements for an implantable artificial heart remain daunting. Since the long term objectives of practitioners in the medical arts include a practical implantable artificial heart that a recipient may rely upon for long periods of life independent and free of medical supervision, reliability becomes of paramount importance.
Accordingly, and by way of example, a successful artificial heart replacement device must, above all, be long lasting and reliable. The dire consequences to the device recipient brought about by device failure make this requirement all too apparent. In addition, however, the device must be small enough to be implantable within the recipient's chest and efficient enough to maintain adequate blood circulation to sustain normal life functions. The device must avoid undue stress upon the recipient's circulatory and pulmonary systems. The device must also be capable of adjusting to and compensating for different recipient activity levels and stresses.
One type of pump which has begun to show promise as a type of pumping apparatus suitable for use within an artificial human heart involves rotatable turbine type pumps. While a variety of turbine style pumps have been tried in application to artificial hearts, most utilize a rotating center shaft which supports a plurality of outwardly extending turbine blades or vanes. While turbine pumps show promise, the complex nature of human blood presents a significant number of daunting problems which, as of yet, remain largely unsolved. For example, early on in the application of turbine style pumps it became clear to practitioners that the use of conventional high-speed turbines produced unacceptable damage to blood cells. Further problems arise in that blood tends to coagulate and form like threatening clots in areas of the circulatory system or pumping apparatus in which blood is relatively static and tends collect. Still further problems arise as blood tends to form undesired clots against edges within the pumping structure. By way of further example, still more problems are created as rotating blades and vanes of turbine pumps induce corresponding turbulence and “swirling” flow patterns within the pump blood.
Accordingly, these additional requirements such as induced flow turbulence, avoidance of blood cell damage by the pumping apparatus and the prevention of the blood clot forming stagnation regions make further demands upon the heart replacement device.
In addition, because such artificial heart devices are implanted within the human recipient's chest cavity, it is essential that the size, shape and orientation of the artificial heart device the conducive to the confines of the recipient's body. Accordingly, it is an important aspect of the acceptability and practical utility of such artificial heart devices that the device minimize the intrusive potential of the device implant.
One such artificial heart device which embodies great promise, is shown in the above-referenced and incorporated U.S. Pat. No. 9,314,559 which sets forth an artificial heart for use in a human recipient that includes a housing within which a quartet of turbine pump segments are operative. The quartet of turbine pump segments provides a redundancy which in turn enhances the safety factor provided by the artificial heart. A controller is powered by a rechargeable battery and is operative to apply appropriate drive signals to the motor drives of the turbine pump segments. The battery may be implanted along with the controller to avoid the need for any external connections to the artificial heart. An inductively coupled battery charger for use outside the recipient's body is positioned proximate the battery charger to provide inductively coupled charging for use in driving the artificial heart.
A substantial number of recently explored technologies attempting to provide successful implantable artificial hearts have chosen to utilize pumping apparatus which includes a rotating impeller such as a turbine impeller or the like. While rotating turbine impeller type pumps have shown great promise for ventricular assist devices, a limitation has arisen which takes the form of rotational blood flow turbulence created by the rotating impellers of the turbine pumps. This turbulence has been found to exhibit vortex characteristics which are undesirable in application to blood pumping apparatus.
In a related art, various apparatus have been provided for reducing or mitigating the turbulence within fluid flow systems induced by the rotating pumps such as turbine pumps or the like. Such apparatus are often referred to in the art as “deswirlers” or “flow straighteners”. Such devices are typically placed downstream in the fluid flow relative to the rotating pump elements with the object of counteracting the rotational turbulence component in the flow produced by the rotating pump elements. In one such element a type of “fluid collimator” is provided in which a plurality of generally small fluid passages are arranged in a parallel relationship much like a box of drinking straws. In another type of deswirler device, a plurality of vanes are situated within the fluid flow downstream of the rotating pump element.
While practitioners in the medical treatment and medical device arts have created a virtually endless number of proposed artificial heart replacement devices, there remains nonetheless a continuing unresolved need in the art for an improved, implantable, reliable and effective artificial heart replacement device which meets the stringent, unforgiving and vital requirements and challenges posed by a truly fully functioning completely implantable heart replacement device.